express-protocol

Decode protobuf data for express

• With the protobufjs library.
• It's easy to use.

Installation

npm i express-protocol

Usage

For the client example

Include script tag in html

    <script src="https://raw.githubusercontent.com/chenxianming/express-protocol/master/dist/protobuf.min.js"></script>

FE encode data to buffer

  var root = protobuf.parse(`
    syntax = "proto3";
    package awesomepackage;

    message AwesomeMessage {
        optional string stringVal = 1;
        message EmbeddedMessage {
            optional int32 key2 = 1;
            optional string key3 = 2;
        }
        optional EmbeddedMessage embeddedExample1 = 2;
        optional int32 key4 = 3;
        optional string ke5 = 4;
    }
  `).root;

  var AwesomeMessage = root.lookupType("awesomepackage.AwesomeMessage");

  var message = AwesomeMessage.create({
      stringVal:'123',
      embeddedExample1:{
          key2:1,
          key3:'123'
      },
      key4:123,
      key5:'111'
  });

  var buf = AwesomeMessage.encode(message).finish();
  var arr = buf.toString();

  //Send array string to server
  post( {protoBuf:'['+arr+']' } )

If you completed setup server, try to encode postdata and decode response data.

The post format like this one , or you can submit "application/json" format.

  $.post('/', {protoBuf:'['+arr+']' }, function( data ){

      var root = protobuf.parse(`
          syntax = "proto3";
          package test;

          message Message {
            optional string msg = 1;
            message ResultMessage {
                required int32 statusCode = 1;
                required int32 count = 2;
                message Listobj {
                  required string key1 = 1;
                  required int32 key2 = 2;
                }
                repeated Listobj list = 3;
            }
            optional ResultMessage result = 2;
          }
      `).root;

      var arr = [];

      var proto = root.lookupType("test.Message");

      var buf = new Uint8Array( data.protoBuf );

      console.log( proto.decode(buf).toJSON() );
  });

You will recived an array to parse.

Log the decode result;

For the node client( Example for post encode only )

let buf = AwesomeMessage.encode(message).finish();

let data = buf.toJSON().data;

let postArr = [];

data.forEach( a => postArr.push( a ) );

let arr = '['+postArr+']';

    //send postdata to server
request( {protoBuf:arr} );

For the server route

const ExpressProtocol = require("express-protocol");

let indexDecode = new ExpressProtocol({
  packName: "awesomepackage.AwesomeMessage",
  parse: `
      syntax = "proto3";
      package awesomepackage;

      message AwesomeMessage {
          optional string stringVal = 1;
          message EmbeddedMessage {
              optional int32 key2 = 1;
              optional string key3 = 2;
          }
          optional EmbeddedMessage embeddedExample1 = 2;
          optional int32 key4 = 3;
          optional string ke5 = 4;
      }
  `,
  sendName: "test.Message",
  send: `
    syntax = "proto3";
    package test;

    message Message {
      optional string msg = 1;
      message ResultMessage {
          required int32 statusCode = 1;
          required int32 count = 2;
          message Listobj {
            required string key1 = 1;
            required int32 key2 = 2;
          }
          repeated Listobj list = 3;
      }
      optional ResultMessage result = 2;
    }
  `
});

router.post("/", indexDecode.decode(), function(req, res, next) {

    //You will recived a json data from req.body.protoData          
    console.log( req.body );

    //And you can see the buffer data in the client response.
    res.json({
        msg: "ok",
        result: {
            statusCode: 200,
            list: [
                {
                    key1: "123",
                    key2: 456
                },
                {
                    key1: "test",
                    key2: 789
                }]
        }
    });

});

Config / syntax

let indexDecode = new ExpressProtocol({
    packName:'Index, to get the proto function object',
    parse:'Text, protocol buffer descriptor',
    sendName:'options, like a packName, if you want to response protobuf json to client',
    send:'Text, protocol buffer descriptor for response json.'
});

In the express route

router.post("/", indexDecode.decode(), function(req, res, next) {
    //do something
});